Field of the Invention
The present invention relates to a container system for storing a biological tissue sample. More particularly, the present invention is directed to a two container system for storing a biological tissue sample in a reagent or, if so desired, in multiple reagents.
Description of Related Art
Biological samples are often obtained by a researcher or clinician for diagnostic evaluation to determine the presence of certain diseases and to determine an appropriate treatment for the disease. These samples are also obtained for molecular diagnostic and nucleic acid analysis, particularly RNA and DNA analysis, which have become common place in research for the treatment of numerous diseases. An essential requirement for accurate RNA and DNA analysis is the presence of high quality and intact RNA and DNA within the biological sample.
Often times, the histologic or cytologic analysis will be performed immediately after the sample is removed from the patient or source to avoid molecular changes that may occur during storage. These changes, such as gene transcription, result from the degradation of the nucleic acids within the sample caused by exposure of an untreated sample to certain environmental stresses. However, analysis of the sample immediately after the sample is collected is often impossible or impractical. Therefore, it is necessary to provide a system for storing a sample under controlled conditions for a certain period of time while maintaining the structural and molecular integrity of the sample.
Traditionally, one way of accomplishing this storage was by submerging the sample in a single fixative reagent. A typical fixative reagent is 10 percent (%) formalin but may also include water miscible alcohols, ethanol/acetone mixtures, and ethanol/acetic acid mixtures. The containers used for such storage were generally composed of a single integral cavity which could house an effective volume of reagent to treat a particular biological sample. The biological sample, along with the reagent, would be placed in the container, the container would be closed, and the sample could then be stored and transported while being preserved by the fixative agent. An example of such a container can be seen in U.S. Pat. No. 7,147,826 to Haywood et al. These containers have experienced some success in the industry, but are subject to certain limitations.